The present invention is in a pollutant reduction system and more specifically, in a pollution reduction system for nautical craft which utilizes, at least in part, fossil fuel.
Environmental concerns have, in recent years, resulted in legislation affecting chemical and other manufacturing processes as well as fuel consuming vehicles. Nautical craft, which consume fossil fuel for power generation, often generate smoke and pollutant gases during operation.
Technology as applied to nautical craft has always been a specialized area. A prime consideration in nautical craft is the density factor. This requires that any such apparatus or system used in nautical craft occupy a minimum of space without adding significant weight concentrated in that limited space. The continuous exposure to the erosive and corrosive affects of water, especially sea water, requires that any such system or apparatus in service must be able to be constructed of corrosive-resistant materials which still can meet with operational requirements.
While the foregoing requirements are applicable to all nautical craft, they are especially applicable to pleasure craft, workboats and tugboats which generally have comparatively limited available space. Another consideration is that any pollutant control system should require minimum modification to an existing exhaust system with little or no effect on other operational aspects of that exhaust system.
Generally nautical craft use a diesel engine which can produce a densely smokey exhaust including invisible gaseous pollutants.
One approach taken to control vehicle emissions is exemplified in U.S. Pat. No. 3,657,878 to Kaufmann. In this patent, there is disclosed an exhaust system which includes a optimized venturi insert which is coupled mechanically so that with increasing vehicle speed, additional combustion air is introduced in the exhaust to complete combustion. This approach involves the risk of upsetting the balance of exhaust gases versus incoming air and also requires a mechanical linkage which, has no more reliability than any typical mechanical assembly. Also used in the Kaufmann system is the injection of a fluid for reaction. Such an arrangement would not be suitable for use in nautical vessels.
U.S. Pat. No. 3,577,728 to Von Brimer discloses an exhaust gas processing system wherein the exhaust pipe of a vehicle tangentially engages a cylindrical tubular reactor section so that exhaust gas is fed cyclonically into the reactor. The tubular reactor section has an opening such that the suction developed by the centrifugal motion of the exhaust gas products induces additional air. An ignitor or catalytic element is included in the tubular reactor to further advance or complete the combustion of unreacted products. In this arrangement, because of the high centrifugal force which is generated, there is a significant temperature rise within the reactor which, according to the patentee, encourages the combustion reaction. This temperature increase is somewhat diluted by the induction of air due to the cyclonic effect. Further, because of the centrifugal forces generated there is significant opportunity to develop a back pressure and therefore Von Brimer limits the exhaust injection inlet velocity to no more than 80% of sonic velocity.
In another variation of this prior art device the chamber is equipped with a helical baffle member to impart a helical or spiral pattern to the exhaust gases and to insure sufficient residence time within the reactor for a complete combustion. It further aids in absorbing sound energy.
U.S Pat. No. 3,107,484 to Touhey describes an attachment for use in a tail pipe having a number of helical vanes or fins to divert air into the tail pipe to dilute the gases therein. The attachment serves to reduce back pressure at the muffler and engine to increase the efficiency of the engine and to further dilute the exhaust gases with fresh air so that odors, corrosive and toxic qualities of the gas are reduced.
U.S. Pat. No. 4,339,918 to Michikawa discloses an attachment to the end of an automobile exhaust pipe which includes a number of spiral blades to impart a rotary motion to the exhaust gas. The attached tubular member has a first section having a gradually flaring diameter along the direction of exhaust gas flow and a second tubular portion which gradually tapers off in that same direction along with a trumpet-shaped tubular portion, the diameter of which suddenly widens from the smallest diameter portion of the second tubular portion. The spiral blades are disposed in the tubular member between the first and second portion and are of a relatively complicated configuration. The device is especially designed for motor vehicles rather than water craft.
In U.S. Pat. No. 3,016,692 an exhaust arrangement is disclosed wherein a static means surrounds the exhaust outlet to create a suction which accelerates the velocity of the exhaust gases. This purportedly results in better engine efficiency. The device of this patent includes angularly spaced vanes within a tapered nozzle which surrounds the exhaust pipe.
U.S. Pat. No. 3,495,385 to Glass shows an air pollution control device wherein an apertured helical pipe delivers exhaust gas and extends for a portion of its length about the clean gas outlet pipe of the device and a conduit delivering decontaminating liquid from the device to the helical pipe. The apparatus is inserted in the conventional exhaust pipe of an automobile. The exhaust gas experiences a venturi effect because of the conduit opening, which creates a strong vacuum and causes the entraining of liquid particles in the gases wherein they intermix with the pollutants and are transferred into the liquid phase.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention .